Compressor won't fill past 5 bar

[mike 109444]

Well, obviously you need to sit a calibrated child on one end of the 2by4 and measure the current

What through the child ?

 

[trigg]

What through the child ?

Sorry chaps this one’s a no go, I’m not allowed to shock the children anymore.

Anyway stripped down the rest of the pump, crank turns freely, big and small ends all fine, nothing untoward in the crank cases.. Guess I’ll knock up a new head gasket and get it all back together with a bit of a clean. I would do rings as they’re cheap but am reticent to spend any more without knowing what’s going on.

 

[Kram]

I am guessing it was well out of warranty but may be worth sending an email to clarke/machinemart? and see if they can be any help

 

[Chippie]

Thanks @dobbslc makes sense but definitely no leaks, replace the non return valve is one of the first things I did because I wasn't sure about it. It's working fine and the receiver will hold pressure even with the cylinder head disconnected.

@Chippie sounds good. What exactly am I looking for/how much resistance am I trying to apply with the 2x4? If we already know its fine running with no load and struggling with the pump load at 5 bar am I just looking for another reference?

Check how long it takes from a flat receiver to when the motor trips, then load it up with the piece of wood, check the time if the motor trips with the wood pressed against the rim of the pulley, try and monitor the current the motor pulls and if you can, try and keep the current the same as if it were driving the pump…

 

[voipio]

What do the cylinder bores and piston skirts look like, wear-wise? I think it's the bores that are shown in the last couple of pics. If so, they don't appear to be very smooth. I could be wrong, of course.

 

[carbon]

In the first post you give 238v at the plug. Have you checked the voltage with it running all assembled correctly. Are you using an extension lead with this? If the voltage is low the motor speed may be dropping and the start cap might be switching back in causing the current to increase above the 15amp rated trip.

 

[dave h 2]

In the first post you give 238v at the plug. Have you checked the voltage with it running all assembled correctly. Are you using an extension lead with this? If the voltage is low the motor speed may be dropping and the start cap might be switching back in causing the current to increase above the 15amp rated trip.

Either that or we are back to the usual reason for excess current - the motor. BTW searching the motor code MEC 90L throws up a SIP compressor motor.

 

[trigg]

@dave h 2 good spot. It did cross my mind that I couldn't see any Clarke branding/name plate on the motor, but I guessed they just used a different supplier across the model run or something. Maybe a new motor is the way to go..

@carbon have checked running and see 238V at the compressor too while running. Worth a check though.

Piston skirts are fine and nothing untoward with the rings, bore almost looks like it has some galling in the pics but feels smooth under finger, just the one light score mark which doesn't worry me too much.

 

[carbon]

I have seen one three phase 5.5kw motor that a customer had in a machine that couldn’t produce any usable power. I think when it was at idle it was drawing 10 amps and had a max of 13. When the pump was connected to it there wasn’t a lot left to do anything with. I did take it to a local rewind place and they spent quite a time testing it and couldn’t find any obvious fault with it, but admitted that it wasn’t as it should be. It wasn’t cost effective to have it repaired as a new motor was cheaper.